I realized the movie was gonna suck the second Hit-Girl told the guy attacking Dave to "promise he'd never turn to crime again". The thing that made Hit-Girl and Big Daddy so cool was that unlike Dave who followed the classic comic book rules, they understood the limited violence\no killing rule had to be tossed out.

Another massive red flag was when the movie began with Red Mist killing his mother. Screen writing 101, enter late and leave early. In the original scripts for Empire Strikes Back Darth Vader began the movie in a castle where he is given his quest to find Luke Skywalker and bring him to the darkside. However this was thrown out because the audience isn't going to have a hard time accepting Vaders been looking for Luke after the events of the previous film.

Overall the whole things was just a mess. I was pissed when Matthew Vaughn left the project for X-Men but now that he's not even doing that anymore I'm furious.